Aqueous silica slurry and amine carboxylic acid compositions selective for nitride removal in polishing and methods of using them

ABSTRACT

The present invention provides aqueous chemical mechanical planarization polishing (CMP polishing) compositions comprising one or more dispersions of aqueous colloidal silica particles, preferably, spherical colloidal silica particles, one or more amine carboxylic acids having an isolectric point (pI) below 5, preferably, an acidic amino acid or a pyridine acid, and one or more ethoxylated anionic surfactants having a C 6  to C 10  alkyl, aryl or alkylaryl hydrophobic group, wherein the compositions have a pH of from 3 to 5. The compositions enable good silicon nitride removal and selectivity of nitride to oxide removal in polishing.

The present invention relates to aqueous chemical mechanicalplanarization (CMP) polishing compositions comprising an abrasive of oneor more dispersions of colloidal silica particles, such as sphericalsilica particles, one or more amine carboxylic acids having anisoelectric point (pI) below 5, and an ethoxylated anionic surfactanthaving a hydrophobic group, wherein the compositions have a pH of from 3to 5.

As the technology for integrated circuit devices advances, traditionalmaterials such as silicon nitride, silicon dioxide and polysilicon arebeing used in various combinations to achieve and enable desiredarchitectural configurations and device performance. Conventionalpolishing slurries have been designed for “stop on silicon nitride”applications such as in shallow trench isolation (STI). More recently,the density of integrated circuits has continued to increase, leading toa number of new front end of the line (FEOL) structures that benefitfrom CMP polishing, including replacement metal gates, contact plugs,and substrates treated by conductive metallization. In such structures,silicon nitrides serve as the etch stop layer, capping material, andhard mask. In addition, silicon nitride finds increasing use as adiffusion or passivation layer, spacer material, and liner. In all suchschemes, silicon nitride is used in combination with other dielectricfilms such as silicon oxide or tetraethoxysilane (TEOS). Thus, mostpatterned wafers now contain both nitride and oxide dielectric films atdifferent density; further, feature size steps involving suchintegration schemes require selective CMP polishing or removal ofsilicon nitride films without removing the oxide dielectric material.Other methods needing nitride: oxide selective CMP polishingcompositions are “Reverse STI processes” where trenches are etched inthe dielectric oxide and filled with a dielectric nitride cap; andalternatives to conventional “Etch Back processes” where CMP polishingis used in addition to or instead of etching. One such example of thealternative etching process is self-aligned contact (SAC) capping. InSAC capping, replacement metal gates (RMG) have been formed of an excessof metal, such as tungsten, that has been removed by CMP polishing, andthen has been etched down by reactive ion etching (RIE) which formsnarrow gaps in the wafer. The gaps are then filed with silicon nitride(SiN). CMP polishing then removes excess nitride and stops on the oxidesurface.

In each case in the prior paragraph, new FEOL architectures like SACrequire a reverse selectivity, i.e., a high nitride removal rate with alow oxide removal rate, in CMP polishing to remove the excessdielectric. In SAC, complete clearing of the nitride layer over existingoxide layers is critical to avoid blocking oxide etching in successivesteps. However, over polishing of the nitride would thin the nitride SACcap, risking an electrical short. Therefore CMP with high selectivityCMP polishing is critical. The new FEOL architectures all result in astructure in which a predetermined pattern of the dielectric nitride isinlaid in the silicon wafer. Such CMP polishing requires the removal andplanarization of a silicon nitride overburden, thereby resulting in acoplanar surface with the silicon nitride-filled trenches, plugs, orgaps. An acceptable nitride:oxide removal rate ratio is necessary toprevent damage to the underlying Si active areas and provide an overpolish margin to ensure all pattern densities are cleared of thenitride. Further, dishing of the nitride in any trench, cap or gap mustbe avoided to prevent low threshold voltage leaks in finishedstructures.

Presently, users of aqueous chemical, mechanical planarization polishing(CMP polishing) compositions used with CMP polishing pads to polishsubstrates wish to avoid the use of ceria containing CMP polishingcompositions. Silica slurry formulations offer lower cost, defect-freesolutions, but, to date, have suffered from unsatisfactory nitride tooxide selectivity for use, especially on patterned wafers.

U.S. Pat. No. 9,558,959 B2, to Mishra et al. discloses a chemicalmechanical polishing composition for polishing a substrate, thecomposition comprising an anionic abrasive, which may be colloidalsilica dispersion having anionic particles and one or more nitrideremoval rate enhancer, such as a carboxylic acid or its salt. Thechemical species in the silica particles can be an acidic compound. Thenitride removal rate enhancer can be any of scores of compounds and mayinclude amino acetic acid. Of the many such nitride removal rateenhancers and many abrasive species disclosed, however, Mishra fails todisclose any composition in which any amine carboxylic acids whichincreases the selectivity of dielectric nitride:dielectric oxide removalrates. Further, Mishra appears to require both a chemical species in thesilica particle and a separate nitride removal rate enhancer additive.

The present inventors have endeavored to solve the problem of providingaqueous silica slurries which enable acceptable nitride removal andnitride:oxide removal rate selectivity for use in SAC applications, aswell as methods for using the slurries.

STATEMENT OF THE INVENTION

1. In accordance with the present invention, aqueous chemical mechanicalplanarization polishing (CMP polishing) compositions comprise anabrasive of one or more dispersions of colloidal silica particles, suchas, for example, spherical colloidal silica particles, one or more aminecarboxylic acids having an isoelectric point (pI) below 5 preferably,acidic amino acids or pyridine acids having a pI of from 2.0 to 4.0, andone or more ethoxylated anionic surfactants having a C₆ to C₁₆, or,preferably, a C₆ to C₁₀ alkyl, aryl or alkylaryl hydrophobic group,preferably, at least one ethoxylated sulfate surfactant, wherein thecompositions have a pH of from 3 to 5 or, preferably, from 3.5 to 4.5,further wherein, the amount of the abrasive particles as solids, rangesfrom 0.01 to 30 wt. %, or, preferably, from 0.1 to 10 wt. %, or, morepreferably, from 0.1 to less than 1 wt. %, based on the total weight ofthe composition.

2. In accordance with the aqueous CMP polishing compositions as setforth in item 1, above, wherein the weight average particle sizes (CPS)of the abrasive colloidal silica particles ranges in the one or moredispersions of colloidal silica particles or a weighted average of suchparticle sizes in a mixture thereof ranges from 10 nm to 200 nm, or,preferably, from 20 nm to 80 nm.

3. In accordance with the aqueous CMP polishing compositions as setforth in any one of items 1, or 2, above, wherein the one or more aminecarboxylic acids is chosen from acidic amino acids or pyridine acids,or, more preferably, is chosen from nicotinic acids, picolinic acids,glutamic acid or aspartic acid.

4. In accordance with the aqueous CMP polishing compositions as setforth in item 3, above, wherein the total solids amount of the one ormore amine carboxylic acids ranges from 0.005 to 5 wt. % or, preferably,from 0.01 to 1 wt. % or, more preferably, in the amount of from 0.02 to0.5 wt. %, all wt. %s based on the total weight of the composition.

5. In accordance with the aqueous CMP polishing compositions as setforth in any one of items 1, 2, 3, or 4, above, wherein the ethoxylatedanionic surfactant is chosen from ethoxylated sulfates, ethoxylatedsulfonic acid, ethoxylated sulfonate salts, ethoxylated phosphates,ethoxylated phosphonates, or ethoxylated carboxylates, preferably,ethoxylated sulfates.

6. In accordance with the aqueous CMP polishing compositions as setforth in any one of items 1, 2, 3, 4, 5, or 6, above, wherein the amountof the ethoxylated anionic surfactant ranges from 0.0001 to 1 wt. %, or,preferably, from 0.01 to 0.1 wt. %.

7. In accordance with another aspect of the present invention, methodsof using the aqueous CMP polishing compositions comprise polishing asubstrate with a CMP polishing pad and an aqueous CMP polishingcomposition as set forth in any one of items 1 to 6, above.

8. In accordance with the methods of the present invention as set forthin item 7, above, wherein the substrate comprises both silicon dioxideor tetraethoxysilicate (TEOS) and silicon nitrides, as SiN or Si₃N₄ ortheir mixtures, and the polishing results in a nitride:oxide removalrate ratio of at least 8:1, for example, from 8:1 to 200:1 or,preferably, at least 50:1, for example, from 10:1 to 100:1.

9. In accordance with the methods of the present invention for polishinga substrate as in any one of items 7 or 8, above, wherein the polishingdownforce ranges from 6.89 kPa (1.0 psi) to 41.37 kPa (6 psi) or,preferably, from 10.34 kPa (1.5 psi) to 20.68 kPa (3 psi).

10. In accordance with the methods of the present invention forpolishing a substrate as in any one of items 7, 8, or 9, above, whereinthe CMP polishing composition comprises a total of from 0.1 to 5 wt. %,or, preferably, from 0.1 to 3 wt. %, total solids content of thedispersion of the colloidal silica particles, preferably, sphericalcolloidal silica particles. The CMP polishing compositions may be storedand shipped as a concentrate and then diluted with water at the time ofpolishing the substrate.

Unless otherwise indicated, conditions of temperature and pressure areambient temperature and standard pressure. All ranges recited areinclusive and combinable.

Unless otherwise indicated, any term containing parentheses refers,alternatively, to the whole term as if no parentheses were present andthe term without them, and combinations of each alternative. Thus, theterm “(poly)isocyanate” refers to isocyanate, polyisocyanate, ormixtures thereof.

All ranges are inclusive and combinable. For example, the term “a rangeof 50 to 3000 cPs, or 100 or more cPs” would include each of 50 to 100cPs, 50 to 3000 cPs and 100 to 3000 cPs.

As used herein, the term “amine carboxylic acid” means any organiccompound which contains at least one carboxyl group and at least oneamine or ammonia group. As used, an “amine carboxylic acid” is notlimited to naturally occurring amino acids or just those amino acidsthat form peptide bonds. For example, pyridine carboxylic acids areamino acids that are not likely to form peptide bonds.

As used herein, the term “ASTM” refers to publications of ASTMInternational, West Conshohocken, Pa.

As used herein, the term “colloidally stable” means that a givencomposition does not gel or precipitate, and remains clear upon visibleinspection after a given time and at a given temperature.

As used herein, the term “isolectric point” or “pI”, for an aminecarboxylic acid is the pH at which the amine carboxylic acid does notmigrate in an electric field or electrophoretic medium; the pI refers to(i) the average of the two pKas in). A detailed explanation of“isoelectric point” and its calculation follows in the examples, below.Further, as used herein, the term “pI of the total abrasive” means aweighted average of the pI of each of the one or more dispersions ofcolloidal silica particles. Thus, if there is one such dispersion ofcolloidal silica particles, then the pI of the total abrasive equals thepI of that dispersion; if there is a 50/50 w/w mixture of two suchdispersions and the pI of one such dispersion is 3.5 and the pI of theother such dispersion is 4.5, then the pI of the total abrasive is(3.5×0.5)+(4.5×0.5) or 4.0.

As used herein, the term “ISO” refers to publications of theInternational Organization for Standardization, Geneva, CH.

As used herein, the term “Particle size (CPS)” means the weight averageparticle size of a composition as determined by a CPS Instruments (TheNetherlands) disc centrifuge system. The particles are separated by sizeusing centrifugal forces in a solvent and quantified using optical lightscattering.

As used herein, the term “silica particle solids” or “silica solids”means, for a given composition, the total amount of spherical silicaparticles, plus the total amount of elongated, bent or nodular silicaparticles, including anything with which any of those particles aretreated.

As used herein, the term “solids” means any material other than water orammonia that does not volatilize in use conditions, no matter what itsphysical state. Thus, liquid amine carboxylic acids, or additives thatdo not volatilize in use conditions are considered “solids”.

As used herein, the term “strong acid” refers to protic acids having apK_(a) of 2 or less, such as inorganic acids like sulfuric or nitricacid.

As used herein, the term “use conditions” means the temperature andpressure at which a given composition is used, including increases intemperature and pressure during or as a result of use.

As used herein, the term “weight fraction silica” means the total wt. %of silica, based on the total weight of the composition/100%. Thus, 30wt. % silica equates to a weight fraction of 0.3.

As used herein, the term “wt. %” stands for weight percent.

As used herein, the term “zeta potential” refers to the charge of agiven composition as measured by a Malvern Zetasizer instrument. Unlessotherwise indicated, all zeta potential measurements were made on(diluted) slurry compositions as described in the examples. The reportedvalue was taken from an averaged measurement of zeta values using >20acquisitions taken by the instrument for each indicated composition.

The present inventors have surprisingly found that an aqueous CMPpolishing composition of an abrasive of colloidal silica particles whichcontain an anionic charge and an amine carboxylic acid having anisoelectric point below 5 enables never before achieved removal rateselectivity of dielectric nitrides substrates, such as silicon nitrides,to dielectric oxide substrates, such as silicon oxides.

The aqueous CMP polishing compositions in accordance with the presentinvention provide a dielectric nitride: dielectric oxide: substrateremoval rate selectivity ratio of from 8:1 to 30:1, or, preferably, from10:1 to 20:1. The selectivity ratio is improved at the preferred pH of3.5 to 4.5 and when using a higher concentration of the preferred aminecarboxylic acid. The methods in accordance with the present inventionenable to provision of the dielectric nitride:dielectric oxide removalrate selectivity ratio of from 8:1 to 200:1, or, preferably, from 10:1to 100:1.

Preferably, in accordance with the present invention the dielectricoxide and dielectric nitride substrates are, respectively, siliconoxides and silicon nitrides.

In accordance with the present invention, suitable colloidal silicacompositions may comprise a dispersion of silica made by conventionalsol gel polymerization or by the suspension polymerization of waterglass so as to produce a plurality of spherical colloidal silicaparticles, or of elongated, bent or nodular silica particles in adistribution or mixture that may include a plurality of colloidal silicaparticles of various sizes.

The one or more amine carboxylic acids in accordance with the presentinvention has a pI expressed as a pI equal to or less 5, or, preferably,from 2.0 to 4.0. Further, the present invention encompasses compositionscomprising mixtures of more than one amine carboxylic acids; in such acase the pI of the amine carboxylic acid mixture is the weighted averageof the pI of each amine carboxylic acid (in the same way as with thetotal abrasive as disclosed, above).

The aqueous CMP polishing compositions in accordance with the presentinvention have a negative zeta potential because they are used at a pHabove their isolectric point. Preferably, the abrasive in the aqueousCMP polishing compositions of the present invention have a zetapotential of from −5 to −20 mV. Such a zeta potential helps controlremoval rates by increasing the nitride removal rate.

To improve the dielectric nitride removal rate achieved when using theaqueous compositions of the present invention, the compositions of thepresent invention may further comprise polymers or anionic groupmodified structures of amine carboxylic acids.

The aqueous CMP polishing compositions of the present invention maycomprise other additives, such as (poly)aspartic acids, in amounts of upto 1 wt. %, based on total solids.

Desirably, the CMP polishing of the present invention is carried outsuch that the silicon nitride is substantially removed and the silicondioxide is adequately planarized without excessive erosion or dishing ofdielectric nitride.

In use, CMP polishing of a wafer substrate involves providing a siliconsubstrate on which is deposited a layer of silicon oxide. Followingmetallization or photolithography, trenches, holes, hollows or gaps areetched onto the substrate comprising an overlying layer of siliconoxide, and an excess of dielectric, for example, silicon nitride isdeposited thereon. The substrate is then subjected to planarizationuntil the surface layer of silicon nitride is substantially removed andthe surface layer of silicon oxide is exposed but not substantiallyremoved, such that the dielectric or silicon nitride remaining in thetrenches is approximately level with the silicon oxide in the edges ofthe trenches, holes, hollows or gaps.

EXAMPLES The Following Examples Illustrate the Various Features of thePresent Invention

In the Examples that follow, unless otherwise indicated, conditions oftemperature and pressure are ambient temperature and standard pressure.

The following materials, including those listed in Table 1, below, wereused in the Examples that follow:

Surfactant A: Witcolate™ 1247H surfactant (Akzo Nobel, Arnhem, NL), aC₆-C₁₀ alcohol ethoxylated ammonium sulfate having 3 ethoxy groups,wherein C₆ comprises 15-21% of the alkyl groups, C₈ comprises 31-38.5%of the alkyl groups and C₁₀ comprises 42-50% of the alkyl groups.

TABLE 1 Silica and Other AbrasiveParticles Particle size ConcentrationAqueous Silica Slurry Source pH² (CPS, nm) Morphology Raw Materials (wt.% solids) pI Slurry A Kleboso ™^(, 1) 1598-B25 7.7 38 Spherical NaSilicate 30 <2 ¹ Merck KgAA, Lamotte, France; ²pH as delivered fromsource.

The various silica particles used in the Examples are listed in Table 1,above. Each of the slurries tested contained anionic silica which wasmade anionic by keeping the pH of the abrasive composition above its pI.

The following abbreviations were used in the Examples that follow:

POU: Point of use; RR: Removal rate.

Isoelectric Points Of Amine Carboxylic Acids: The isoelectric point orpI of an amine carboxylic acid is the pH at which the amine carboxylicacid does not migrate in an electric field or electrophoretic medium.Amine carboxylic acids having neutral side chains are characterized bytwo pKas: pKa1 for the carboxylic acid and pKa2 for the amine. The pIwill be halfway between, or the average of, these two pKas, i.e. pI=1/2(pKa1+pKa2). At a pH below pKa1, the amine carboxylic acid will have anoverall positive charge and at a pH above pKa, the amine carboxylic acidwill have an overall negative charge. For the simplest amine carboxylicacid, glycine, pKa1=2.34 and pKa2=9.6, pI=5.97. Acidic amine carboxylicacids have an acidic side chain. The pI will be at a lower pH becausethe acidic side chain introduces an extra negative charge. For example,for aspartic acid there are two acid pKas, (pKa₁ and pKa₂) and one aminepKa, pKa₃. The pI is halfway between these two acid pka values, i.e.pI=1/2 (pKa₁+pKa₂), so pI=2.77. Basic amine carboxylic acids have a pIat a higher pH because the basic side chain introduces an extra positivecharge. For example, for histidine, pI is halfway between two ammoniahydrogen pKas. pI=1/2 (pKa₂+pKa₃), so pI=7.59. The pI of many aminecarboxylic acids is shown in Table 2, below.

TABLE 2 Pkas And Isoelectric Points Of Amino Acids Amine Carboxylic acidpKa1 pKa2 pKa3 pl Aspartic acid 1.88 3.65 9.6 2.77 Glutamic acid 2.194.25 9.67 3.22 nicotinic acid 2 4.85 3.425 picolinic acid 1.07 5.25 3.16Cysteine 1.96 8.18 — 5.07 Asparagine 2.02 8.8 — 5.41 Phenylalanine 1.839.13 — 5.48 Threonine 2.09 9.1 — 5.6 Glutamine 2.17 9.13 — 5.65 Tyrosine2.2 9.11 — 5.66 Serine 2.21 9.15 — 5.68 Methionine 2.28 9.21 — 5.74Tryptophan 2.83 9.39 — 5.89 Valine 2.32 9.62 — 5.96 Glycine 2.34 9.6 —5.97 Leucine 2.36 9.6 — 5.98 Alanine 2.34 9.69 — 6 Isoleucine 2.36 9.6 —6.02 Proline 1.99 10.6 — 6.3 Histidine 1.82 6 9.17 7.59 Lysine 2.18 8.9510.53 9.74 Arginine 2.17 9.04 12.48 10.76

The following test methods were used in the Examples that follow:

pH at POU: The pH at point of use (pH at POU) was that measured duringremoval rate testing after dilution of the indicated concentratecompositions with water to the indicated solids content.

Example 1 Polishing and Removal Rate

Blanket wafer removal rate testing from polishing on each of tetraethoxysilane (TEOS), silicon nitride and amorphous silicon (aSi) substrateswas performed using a Strasburgh 6EC 200 mm wafer polisher or “6EC RR”(Axus Technology Company, Chandler, Ariz.) at a downforce of 20.68 kpa(3 psi) and table and carrier revolution rates (rpm), respectively, of93 and 87, and with an IC1000™ CMP polishing pad having a 1010 groovepattern (Dow, Midland, Mich.) and the indicated abrasive slurry, asshown in Table 3, below, at a given abrasive slurry flow rate 200ml/min. A SEASOL™ AK45 AM02BSL8031C1 diamond pad conditioner disk (KinikCompany, Taiwan) was used to condition the polishing pad. The polishingpad was conditioned in situ during polishing using a down force of 3.17kg (7.0 lbf) at 10 sweeps/min from 4.32 cm to 23.37 cm from the centerof the polishing pad. The removal rates were determined by measuring thefilm thickness before and after polishing using a KLA-Tencor™ FX200metrology tool (KLA Tencor, Milpitas, Calif.) using a 49 point spiralscan with a 3 mm edge exclusion. Removal Rate results and their ratios(selectively) are shown in Table 3, below.

Each of the slurries in Table 3, below was adjusted to the indicated pHwith the indicated additive. The compositions are free of ethoxylatedanionic surfactants.

TABLE 3 Slurry Formulation Details, Removal Rates (RR) and SelectivitiesSolids Additive Zeta potential SiN RR TEOS RR, aSi RR SiN:TEOS SiN:aSiEx. No. Slurry (wt. %) Additive (wt. %) pH (mV) (Å/Min) (Å/Min) (Å/Min)RR ratio RR ratio  1* A 3 H₃PO₄ 0.009 4.0 −17 245 57 — 4.3 —  2* A 3HNO₃ 0.006 4.0 −17 100 67 161 1.5 0.6 3 A 3 picolinic acid 0.25 3.9 −15946 58 48 16.2 19.7 4 A 3 picolinic acid 0.1 4.3 −18 922 48 178 19.0 5.2*Denotes Comparative Example.

As shown in 3, above, the aqueous abrasive slurry compositions inExamples 3 to 4 having amine carboxylic acids with an isoelectric pointof <5, all achieve a high nitride RR but suppress oxide RRs withincreasing additive concentration. These examples provide good nitrideto oxide polish selectivity, especially where the pH of the compositionslies at 4.0 or below. By comparison, the same compositions havingphosphoric acid or nitric acid gave lower nitride RRs and hence nitrideto oxide selectivity is lower.

In the examples in Table 4, below, Comparative examples 10, 11 and 12were adjusted with nitric acid to the indicated pH. All compositions inTable 4 are free of ethoxylated anionic surfactants.

TABLE 4 Slurry Formulation Details, Removal Rates (RR) and SelectivitiesSolids Additive Zeta potential SiN RR TEOS RR, aSi RR SiN:TEOS SiN:aSiEx. No. Slurry (wt. %) Additive (wt. %) pH (mV) (Å/Min) (Å/Min) (Å/Min)RR ratio RR ratio 5 A 3 aspartic acid 0.02 4.0 −16 846 66 — 12.9 — 6 A 3glutamic acid 0.06 4.0 −17 835 64 — 12.9 — 7 A 3 picolinic acid 0.2 3.9−15 946 58 48 16.2 19.7 8 A 3 picolinic acid 0.1 4.3 −18 922 48 178 19.05.2 9 A 3 nicotinic acid 0.1 3.8 −17 923 57 96 16.2 9.6 10* A 3 cysteine0.24 4.0 −22 349 51 132 6.9 2.6 11* A 3 glycine 0.15 4.0 −19 258 48 2345.4 1.1 12* A 3 arginine 0.35 4.0 −4 360 247 421 1.5 0.9 *DenotesComparative Example.

As shown in In

Each of the slurries in Table 3, below was adjusted to the indicated pHwith the indicated additive. The compositions are free of ethoxylatedanionic surfactants.

Table 3: Slurry Formulation Details 4, above, amine carboxylic acidshaving an isoelectric point of above 5 (also pI of the silicon nitridesubstrate), such as cysteine, glycine, arginine have low SiN RRs andmuch silicon nitride lower selectivity. See Comparative Examples 10, 11and 12. The inventive Examples 5 to 9 with amine carboxylic acids havinga pI of below 5 all worked well.

In the examples in Table 5, below, surfactant A was included in Example14 at 0.0125 wt. %, based on the total weight of the composition.

TABLE 5 Slurry Formulation Details, Removal Rates (RR) and SelectivitiesSolids Additive Zeta potential SiN RR, TEOS RR, aSi RR, SIN:TEOS SIN:aSiEx. No. Slurry (wt. %) Additive (wt. %) pH (mV) Å/min Å/min Å/min RRratio RR ratio 13 A 3 nicotinic acid 0.1 3.8 −17 923 57 96 16.2 9.6 14 A3 nicotinic acid 0.1 3.8 −24 930 43 42 21.6 22.1 * Denotes ComparativeExample.

As shown in Table 5, above, addition of Surfactant A (C₆-C₁₀ alcoholethoxylated sulfate) in Example 14 improved selectivity between SiN tooxide selectivity as well as SiN to aSi selectivity.

In the examples in Table 6, below, the indicated aqueous CMP polishingcompositions were formulated at the indicated solids loading using thecomponents in Example 14. However, the polishing experiments were doneon 300 mm blanket wafers (TEOS, silicon nitride) using Reflexion™polisher (Applied Materials, Santa Clara, Calif.). Process conditionswere same as those used in Example 14, above.

TABLE 6 Slurry Formulation Details, Removal Rates (RR) and SelectivitiesSolids Nicotinic Surfac- SiN TEOS Ex. (wt. % acid tant A RR, RR,SiN:TEOS No slurry A) (wt. %) (wt. %) pH Å/min Å/min RR ratio 15 0.16250.0125 0.00068 4.1 290 2 149 16 0.1625 0.025 0.00068 3.9 498 3 174 170.1625 0.05 0.00068 3.7 545 3 216 18 0.325 0.025 0.00135 4.0 583 7 87 190.325 0.05 0.00135 3.8 628 8 79 20 0.325 0.1 0.00135 3.7 668 9 74 210.75 0.05 0.00313 3.8 822 18 45 22 0.75 0.1 0.00313 3.7 895 20 45 230.75 0.2 0.00313 3.6 859 29 30 24 3 0.2 0.0125 3.7 1392 106 13 25 3 0.40.0125 3.6 1408 127 11 26 3 0.8 0.0125 3.5 1416 171 8 27 9 1.2 0.03753.5 2164 634 3 28 12 0.8 0.05 3.7 2350 826 3 29 15 1 0.0625 3.7 23941051 2

As shown in Table 6, above, a greater than 100 nitride to oxideselectivity, suitable for stop on oxide applications, is achieved whilepolishing with inventive compositions containing surfactant A, evenbelow a 1 wt. % abrasive solids loading, based on the total weight ofthe composition; and, further, a greater than 2000 Å/min SiN RR,suitable for bulk SiN polishing, was achieved at a high abrasive solidsloading.

1. An aqueous chemical mechanical planarization polishing comprising anabrasive of one or more dispersions of aqueous colloidal silicaparticles, 0.005 to 5 wt %, based on the total weight of thecomposition, of one or more amine carboxylic acids having an isoelectricpoint below 5 chosen from nicotinic acids and pyridine acids, and one ormore ethoxylated anionic surfactants having a C₆ to C₁₆ alkyl, aryl oralkylaryl hydrophobic group, wherein the composition has a pH of from 3to 5, and, further wherein, the amount of the abrasive particles assolids, ranges from 0.01 to 30 wt. %, based on the total weight of thecomposition.
 2. The aqueous chemical mechanical planarization polishingcomposition as claimed in claim 1, wherein the abrasive comprisesspherical colloidal silica particles.
 3. The aqueous chemical mechanicalpolishing composition as claimed in claim 1, wherein the one or moreamine carboxylic acids have an isoelectric point from 2.0 to 4.0. 4-5.(canceled)
 6. The aqueous chemical mechanical polishing composition asclaimed in claim 1, wherein the amount of the abrasive particles assolids, ranges from 0.1 to less than 1 wt. %, based on the total weightof the composition.
 7. The aqueous chemical mechanical polishingcomposition as claimed in claim 1, wherein the pH of the compositionranges from 3.5 to 4.5.
 8. The aqueous chemical mechanical polishingcomposition as claimed in claim 1, wherein the one or more ethoxylatedanionic surfactants has a C₆ to C₁₀ alkyl, aryl or alkylaryl hydrophobicgroup.
 9. The aqueous chemical mechanical polishing composition asclaimed in claim 1, wherein the ethoxylated anionic surfactant is chosenfrom ethoxylated sulfates, ethoxylated sulfonic acid, ethoxylatedsulfonate salts, ethoxylated phosphates, ethoxylated phosphonates, orethoxylated carboxylates.
 10. The aqueous chemical mechanical polishingcomposition as claimed in claim 9, wherein the amount of the ethoxylatedanionic surfactant ranges from 0.0001 to 1 wt. %, based on the totalweight of the composition.